Motor vehicle braking system



July 9, l940 P. F. RossMANN 2,206,976 MoToE VEHICLE BRAKING SYSTEM FiledDec. 3. 1936 Y "'IIIIIII INVNTOR. vZg-er I 570551724171?.

ATTORNEYS.

] Y Parenteel .my 9, 194e UNITED STATES PATENT OFFICE :auswMOTOR-VEHICLE BEARING SYSTEM Peter F. Detroit, Mich., assignor toPackard Motor Car Company, Detroit, Mich., a corporation of MichiganApplication December 3, 1936, Serial No. l14 ,044 1 4Clalms.

fective for operating mechanisms. The physical' effort required withsuch systems is often greater than the average person cares to exert andespecially when the applications are frequent. For l example, theoperation of motor vehicles in heavy traiiic requires frequent actuationof the brakes and the physical effort required of the operator for thispurpose is fatigulng. It is an object of this invention to reduce the lphysical eifort required to apply duid pressure in the actuation ofmechanism, such as braking mechanism for motor vehicles.

Another object of the invention is to provide a fluid actuatingmechanism in which pressure is exerted jointly on the fluid by theapplication of physical force and mechanically Adeveloped force underphysical control. v

Another object of the invention is to provide a braking system for motorvehicles that can be operated with minimum physical exertion.

- I Another object of the invention is to relieve the driver of some ofthe physical eifort now required in applying the brakes of a motorvehicle. Other objects of the invention will appear from the followingdescription taken in connection with the drawing, which forms apart .of

this specification. and in which: l

- Fig. 1 is a plan view of a motor vehicle'chassis l having my inventionincorporated therewith:

Fig. 2 isan enlarged view, partly in section, of aportion of a brakingSystem by means of which fluid is placed under pressure;

Fig. 3 is a fragmentary sectional view of a portion of the mechanicallydriven pressure means and control mechanism therefor taken on line 3 3of Fig. 2:

' Fig. 4- is-a sectional view of the mechanical drive and controlmechanism therefor taken onv lined-'4 of Pis. 2;

5 ng. 5 ne Seemann-viewer the mechanical a5 with the axle inc a relationto be driven- (Cl. 18S-152) by mechanism contained therein. An'internal, combustion engine l5 is suitably supported upon A the chassisframe and has the usual clutch contained within a housing I6y totransmit power from the engine crankshaft to the driven trans- 5 missionshaft I1 containedwlthin the housing i8. Between the shaft I1 and theclutch is arranged conventional gear mechanism by means Iof which theshaft I1 is rotated at various speeds relative to the speed of thecrankshaft rotation. lo A propeller shaft I9 is connected in aconventional manner with a sleeve 20 splined on the driven shaft I1 andthe propeller shaft transmits power to the mechanism contained withinthe rear axle housing I2 for driving the wheels I 4.` 15

Associated with each of the wheels is a brake drum 2l and associatedwith each brakel drum is a pair of pivotally mounted brake shoes 22.With each pair of brake shoes is associated mechanism adapted to beexpanded for applying the shoes to thedrums 35 and to be contracted forreleasing the shoes from the drums. Such' brake mechanisms are arranged-to be actuated by a hydraulic system comprising conduits convtainingfluid. The front brake mechanisms are 2t connected by a conduit 23 andthe -rear mechanisms are connected by a conduit 24. Connecting theseconduits 23 and 24 is ay conduit 25 ex- -tending longitudinally of thevehicle.

Associated with this fluid system for applying 80 pressure to` actuatethe brake mechanisms is a means comprising 'a casing 26 having a piston21 therein and a fluid reservoir 28 communicating at 2l with theinterior of the casing. A suitable connection 30 establishescommunication 36' between the fluid conduit 25 and the interior of thecasing'. Associated with the :piston is a rod 3l pivoted at 32.to thebrake foot lever 33,-such lever being mounted in the usual manner on a lshaft Il suitably fixed on the chassis. 40

The vehicle 'and braking system so far described are of a conventionaltype except that the piston 21 and its casing are much smaller in ldiameter than those heretofore employed. Ordia narily the application ofphysical force bythe driver against the foot lever ,33 will move the rod'Il andthe piston 21 toward the left, as viewed in Fig. 2, creatingpressure aga'nst iiuid in the 'conduits and thereby expanding Vthebrake' mechanisms 35 to engage the shoes 22 withthe 50 .brake drums onthe wheels.

Ordinarily, with a braking mechanism ofthe described type, the driver isrequired to exert the entire force used to'lapply the brakes and toAmany drivers the extent ofthis force application wy A:ai

is undesirable and to the average driver the applicationof forcerequired for applying-the brak- -ing system in heavy traiic isfatiguing.

In order to relieve the driver of some of the physical eifort nowrequired in applying a braking system, I propose to associate with such'by bolts 4|. shaft l1 extends through this nousing and splined thereon,within the housing, is a clutch drive disk l2 having a friction ringfixed around the rear face thereof. forwardly extending sleeve ange ofthe housing I0 is a shiftable driven clutch element 43, this 'element'being movable axially and being .oscillated when moved to engageagainst the clutch disk I2. On the periphery of the shiftable drivenclutch disk 43 is formed a pair of similar cam lobes M and 45. This camlobe peripheral portion of the driven clutch disk engages a roller I8carried by the'inner end of the piston rod 41 which extends through andis guided by a sleeve I8 formed as a part of the casing Il.

Associated with the fluid system is an auxiliary pressure meansconsisting of a casing or cylinder 49 in which is mounted a plunger il.A suitable connection Il establishes open communication between theinterior of the cylinder and the conduit 2l. By moving the driven disk43 axially into engagement with the driving disk 42 it will be'oscillated to cause .one of the lobe portions to move the same in adirection to operate the piston Il in a direction to exert pressureagainst fluid in the braking system.

This clutch drive is under the control of the foot pedal 33 and theclutch is controlled'to cause actuation of the plunger Il concurrentlywith the physical actuation of the piston 21 and by means'of the samelever movement. m order to so control the clutch of the drivingmechanism for the piston il I provide a fluid conduit I! which isconnected at one end with a casing Il having a reservoir Il in opencommunication therewith and containinga piston It. Associated with thepiston is rod il which is pivoted to the fooil lever as indicateur ss.The other end ofthe fluid conduit Il extends through the krear wall ofthe casing 4l and is arranged in I communication with an expansiblestiif diaphragm means il. Ring members Il are fixed to the forward andrear ends oi the diaphragm means and on the forward peripheral face ofthe front ring is fixed a pair of cam ele-- ments as indicated at Il.'I'he rear ring member Il is suitably fixed to the rear wall of thecasing Il. 'Ihe clutch member Il is provided with ilanges l2 forcarrying shafts t! on which rollers are moimted. There are two of suchArollers and they are arranged diametrically and Telescoping apedal Iloscillates the same to move the rod Si v forward and the'rod l1rearward. Piston 21 moves forward with the rod Il to create pressureagainst nuid in the conduits 28, 2| and Il. Piston it moves rearwardlywith rod Il and creates pressure against the iluid in conduit 53 toexpand the diaphragm Il axially. Before expansion of the diaphragmrollers 6l engage the peak portions of cams li, as shown in Fig.3, andretain such relation until the expanding diaphragm moves ,the clutchmember into engagement with the driven clutch element I2. Engagement ofthe element with element 4I causes it to turn and thus move the rod 41and piston ljl in a direction creating pressure on the fluid in theconduits 23, 2l and 2B. Turning of the cam changes the position of therollers M with respect to the cams 6i so that the rollers ride down thecams in a direction away from the peak portions until the member l! isno longer held in driven engagement with the drive cam member I2. Ofcourse the extent of the diaphragm expansion axially determines theposition of the cams, and further pressure against the pedal willincrease the pressure applied by piston 21 and will also move piston Sito further expand the diaphragm thus moving the cams 6I to again engagethe clutch member Il with the drive member I2 and thereby further movethe piston Il in av direction exerting more pressure on the iluid in thesystem. The operator can feel the position of the brakes when the pedalis depressed because the reaction of pressure in the system will betransferred through the piston 21 and rod 3l to the foot lever. He willthus know to what degree the brakes are applied. 'I he two cam surfacesll and II serve to actuate the/piston Il in the same manner uponengagement of the clutch element with element 42 in either direction ofthe rotation of shaft I1. I

The actionof fluid pressure against the piston Il reacts on the rollerIt creating a force suilicient to urge the clutch member 43 back to theneutral position, as shown in Fig. 5, where the rollers li will bearagainst the foremost portions of cams Il. Springlt holds the piston 50against its rod 41 and exerts a force sufilcient to retain roller II inits neutral position, as shown in Fig. 5, when the pressure in thesystem is low. In this manner the clutch mechanism is moved toineffective position, as shown in Figs. 3 and 5, when the foot lever' llis moved in a direction to retract the diaphragm.

.spring 'Ii holds piston 21 against its rod 3| and spring 12 holdspiston It against its rod 51. Upon release of the foot leverconventional springs (not shown) can .be used to swing the brake shoesaway from their drums and the lever will be returned to position shownin Fig. 2 by spring 'Il suitably xed to a part of the chassis. Pressureon the fluid in the system is now entirely relieved.

In any iiuid system there must be a certain nuid displacement toaccomplish brake application and with the present invention thedisplacement of fluid by the mechanically driven piston lessens by thatamount the displacement required by the application of physical force.As a' although the invention heebeen described in connection with aspecic embodiment, the prini pressure on the liquid in said system,physically operable means connected to move the other of said plungersina direction creating pressure on the liquid in said system, and afluid pressure controlled clutch means for said power driven meanscontrolled by said physically operable means in its plunger operatingmovement.

2. In a brake system, a brake, a liquid system connected to apply saidbrake when pressure is applied to the liquid, a pair of separate meanseach operable to create pressure on the liquid in the system forapplying said brake, physically operable means connected to actuate oneof said pressure creating means, powermeans operable to actuate theother pressure creating means, and clutch control meansl for. the powermeans under control of said physically operablemeans.

3. In abrake system, a brake, a closed liquid system connected to applyv said brake when pressure is applied to the liquid, a pair of separatemeans each operable to create pressure on the liquid in the system forapplying said brake, physically operable4 means connected to one of saidpressurecreating means, power means including a clutch operable toactuate the other pressure creating means,fa pedal connected to Asaidphysically operable means for actuating the same, and means under thecontrol ofv said pedal operable to control said power means clutchwhereby said power means is controlled by movement of said pedal.

4. In a brake system, a brake, conduit means containing liquid forapplying said brake `when,

pressure is applied thereto, a pair of cylinders open to the conduit, aplunger ineach cylinder, a physically operable means for actuating oneof said plungers to create pressure ontheliquid in said system, powermeans including a vclutch y trolled -by the operation of said physicallyoperable means.

PETER F. ROSSMANN.

